Several lines of evidence indicate monoaminergic neurotransmission, environmental stress and their interaction play prominent roles in depression etiology. This project will investigate this process in adolescents and young adults by modeling the direct and interactive effects of environmental risk and candidate genes influencing neurotransmission. Using the National Longitudinal Study of Adolescent Health, mixed regression models will extend existing cross-sectional models through comprehensive examination of several candidate genes and more nuanced conceptualization of environmental risk. Further, using latent curve models, longitudinal analyses of main effects, epistasis and gene-environment interaction (GxE) among candidate genes and environmental risk will model trajectories of depression across adolescence and into young adulthood. Proximate and distal environmental risk will be distinguished and the degree to which proximate environmental factors moderate the main and GxE effects of distal factors will be assessed. Finally, as genetic architecture and social influences may vary by group, effect heterogeneity will be examined by stratifying all analyses by race/ethnicity and gender. [unreadable] [unreadable] [unreadable] [unreadable]